Saw blade tension mechanism for frame saws



Aug. 22, 1950 A. HENDRICKSEN ETAL 2,519,904

SAW BLADE TENSION MECHANISM FOR FRAME SAWS Filed Nov. 18, 1946 2 Sheets-Sheet 1 I0 5 l0 o H H I INVENTORS 4/4917 /4. Hen/vbniran Fave/9 fiend/18 K907 ATTORNEYS Aug. 22, 1950 A. A. HENDRICKSEN ETAL 2,519,904

' SAW BLADE TENSION MECHANISM FOR FRAME sAws Filed Nov. 18, 1946 2 Sheets-Sheet 2 INVENTORS ATI'IJ R N EYs Patented Aug. 22, 1950 SAW BLADE TENSION MECHANISM FOR FRAME SAWS I Allan A. Hendricksen and Francis F. Hendricksen,

Adams, Oreg.

Application November 18, 1946, Serial No. 710,542

d claims. (*Cl. 14533) This invention relates to improvements in saws, and more particularly to the provision of means for tensioning saw blades in frames.

Heretofore, in saws of the type herein considered, the blade has been attached to a frame by means of a pin and wing nut. In a job where it is necessary to change saw blades frequently because of wear or breakage, or because of the necessity of using different types of blades on different metals, the wing nut method oi attaching blades causes a considerable loss of time in changing blades. Also, the wing nut method of attaching blades does not provide the proper tension each time a blade is changed.

It is, therefore, an object of this invention to provide a, spring tensioning device for saw blades which enables blades to be changed quickly and which maintains the proper tension of the blades when changed from time to time.

The above and other objects are attained by the novel construction and arrangement of parts hereinafter described and illustrated by the accompanying drawings, forming a part hereof, and in which:

Fig. 1 is a side elevation-a1 View of a saw with a blade tensioning means in a closed position.

Fig. 2 is a side elevational view with the blade tensioning means in an open position.

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 1.

Fig. 4 is an end View of the device.

Fig. 5 is a longitudinal sectional view of the device.

Fig. 6 is a plan view of a compression lever.

Fig. 7 is a plan view of an operating lever.

Fig. 8 is a section-a1 view taken on the line 8-8 of Fig. 5.

Referring to the drawings, the device is shown to include a saw frame I which is attached by rivets 2 to a hollow handle 6. Mounted in the handle 6 is a guide block 3 having a square hole through which passes the square end 4 of a ten sion rod 4' having a round section 5. The portion 4 has an extension "I from which projects a pin 8 to which one end of a saw blade 9 is attached.

Attached to the handle 6 are pins II! which pass through apertures I I in a compression handle I2, which has apertures I3 receiving pins M on an operating lever I5, the latter having straps I 6 adjacent the end remote from the pins I4 whereby the lever I5 is slidably received on the round section 5 of the tension rod 4'. The end of the lever I5 outwardly of the straps l6 bears against a washer I'I loosely mounted on the round section 5 of the tension rod. A compression spring I8 bears against the washer I1 and against a nut I9 on the threaded end 20 of the rod 4. Access to the nut IQ for adjusting the tension of the spring is attained through an opening 2| in the end of the handle.

In operation, to attach a blade, the compression lever I2 is moved to the position shown in Fig. 5 which relieves the pressure on the spring, allowing the tension rod 4' to be moved longitudinally. The lever I2 is then moved to the position shown in Fig. 1 which applies pressure on washer I1 and provides the proper tension on the blade 9.

To move the blade to a horizontal position as shown in Fig. 2, the compression handle I2 is moved to the open position, and the tension rod 4' is moved so that the round section 5 is in the square hole in the guide block 3. The rod is then rotated to the horizontal position, and the blade attached as above described.

When the compression handle I2 is in the closed position as shown in Fig. 1, the pivot pins I4 of the operating lever I5 are above the pivot pins II) of the compression lever I2, which causes the spring to exert a pressure to hold the opera ing lever or handle up against the hollow handle 6.

The device enables blades to be quickly changed and adjusted to different positions, and provides the proper tensioning of the blades at all times.

The above description is to be considered as illustrative and not limitative of the invention of which modifications can be made without departing from the spirit and scope of the invention as set forth in the appended claims.

The invention having been described, what is claimed is:

1. In a saw, a frame, a hollow handle attached to the frame, a guide block in the handle and having a square hole, a tension rod having a square portion slidably positioned in the square hole of the guide block and a round portion, a washer slidably mounted on the round portion, a nut threaded on the round portion, a compression spring encircling the round portion and bearing against and lying between the washer and nut, a compression lever, means pivoting the same to hollow handle, an operating lever pivoted to the compression lever, and a bearing plate on the operating lever adapted to bear against the washer.

2. In a saw, a frame, a hollow handle connected to the frame, a guide block in the handle, a tension rod slidably mounted in the guide block,

a washer slidably mounted on the rod, a nut threaded on the rod, a compression spring encircling the rod and bearing against and lying between the washer and nut, a compression lever, means pivoting the same to the handle, an operating lever pivoted to the compression lever, and means on the operating lever adapted to bear against the washer.

3. In a saw, a frame, a handle connected to the frame, a tension rod slidably mounted in the handle, means for attaching a saw to the rod, a washer on the rod and a nut threaded on the rod, a spring on the rod between and engaging the washer and nut, a compression lever, means pivoting the same to the handle, an operating lever pivoted to the compression lever, and means on the operating lever adapted to engage the washer.

4. The structure set forth in claim 2 and means in the guide block for preventing rotation of the REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS Number Name Date 833,569 Adamkiewitz Oct. 16, 1906 952,079 McIntire Mar. 15, 1910 FOREIGN PATENTS Number Country Date 525,161 France May 28, 1921 191,105 Great Britain Jan. 1, 1923 

